Boiler systems

ABSTRACT

A boiler system including a boiler chamber to which pulverized solid fuel or liquid fuel can be supplied from a container the system also including a combustion chamber the heated gases from which drive a turbine prior to their use as combustion air in the boiler chamber, the turbine driving a pair of compressors which supply dilution air and an air-fuel mixture respectively to the combustion chamber, a tapping being provided from one of the compressors to pressurize the fuel in the container to ensure its supply to the boiler chamber.

United States Patent Inventor Eric Kellett London, England Appl. No. 12,577 Filed Feb. 19, 1970 Patented Jan. 11, 1972 Assignee C.A.V. Limited Birmingham, England Priorities Feb. 25, 1969 Great Britain 9,908/69; Nov. 21, 1969, Great Britain, No. 52,1 82/69 BOILER SYSTEMS 1 Claim, 1 Drawing Fig.

US. Cl 1 10/104, 263/19 A Int. Cl F23k 3/02 Field of Search 263/ 19;

[56] References Cited UNITED STATES PATENTS 1,955,255 4/1934 Sengstaken 1 10/104 2,103,453 12/1937 Graemiger 110/106 2,839,253 6/1958 Yellott 110/106 X 3,498,593 3/1970 Kellett et a1. 263/19 Primary Examiner-Edward G. Favors Attorney-Holman & Stern ABSTRACT: A boiler system including a boiler chamber to which pulverized solid fuel or liquid fuel can be supplied from a container the system also including a combustion chamber the heated gases from which drive a turbine prior to their use as combustion air in the boiler chamber, the turbine driving a pair of compressors which supply dilution air and an air-fuel mixture respectively to the combustion chamber, a tapping being provided from one of the compressors to pressurize the fuel in the container to ensure its supply to the boiler chamber.

BOILER SYSTEMS This invention relates to boiler systems of the kind including a boiler chamber in which fuel is consumed and means for admitting combustion air and fuel to the boiler chamber.

Such systems are known in which the combustion air is supplied by a motor driven fan and the fuel by means of a high pressure pump when liquid fuel is used or by means of air under pressure when the solid pulverized fuel is used. Such systems require the provision of separate motors and furthermore the provision of an external source of power.

The object of the present invention is to provide such a system in a simple and convenient form.

According to the invention in a system of the kind specified said means comprises a combustion chamber, compressor means for delivering air and fuel to the combustion chamber, a turbine driven by the heated gases leaving the combustion chamber for driving the compressor means first conduit means through which the gases leaving the turbine can be supplied to the boiler as combustion air, and second conduit means through which air under pressure from said compressor means flows to deliver fuel to the boiler chamber.

One example of a boiler system in accordance with the invention will now be described with reference to the accompanying drawings in which reference numeral 10 indicates a boiler which is provided with sets of tubes 11 through which gases from the fire 12 can pass to an outlet conduit 13. The fire 12 is supplied with pulverized fuel through a feed pipe 14 from a bunker l and combustion air is supplied to the fire by way of a conduit 16.

Also provided is a combustion chamber 17 which is supplied with diluting air by means of a compressor 18. The combustion chamber accommodates a burner which is supplied with an air fuel mixture by means of a compressor 19. The two compressors are driven by a turbine 20 which receives the heated gases leaving the combustion chamber 17. Moreover, the conduit 16 is connected to the outlet of the turbine 20 so that the gases leaving the combustion chamber 17 constitute the combustion air for the fire 12. The fuel which is consumed in the combustion chamber 17 may be gaseous or liquid and is supplied from a source 20a.

The outlet 13 from the boiler passes to a heat exchanger 21 which effects heat exchange between the gases leaving the boiler and the gases entering the combustion chamber.

In order to supply the pulverized fuel to the fire bunker is connected by way of a conduit 22 to the outlet of the compressor l8 and the conduit is in communication with the bunker at an upper and a lower point.

In operation, the gases leaving the turbine constitute combustion air for the fire 12 and fuel is supplied to the fire from the bunker. By reducing the quantity of fuel supplied by way of the compressor 19 to the combustion chamber 17, the amount of heat produced in the boiler can be reduced. The maximum output from the boiler is obtained when the maximum allowable quantity of fuel is fed to the combustion chamber 17, this producing the highest temperature which can be tolerated by the blades of the turbine 20. in order to start the boiler system from cold it is necessary first of all to bring the turbine and compressor rotors up to a self sustaining speed prior to the admission of fuel to the combustion chamber and ignition thereof within the combustion chamber. The heated gases leaving the turbine 20 are sufficiently hot to ignite the pulverized fuel supplied by way of the pipe 14 and this avoids the necessity for providing a supplementary ignition means for the fire 12. If desired the gases leaving the heat exchanger 21 can be used to dry fuel for future use.

The bunker 15 can be replaced by a liquid fuel tank and it is only necessary to pressurize the fuel tank to cause the fuel to be forced into the boiler. This provides an extremely convenient method of controlling the output of the boiler system since the pressure of air delivered by the compressor when the latter is of the radial-flow type, is clearly proportional to the mass flow of air.

The system described has the advantage over conventional systems that once started the system is self sustaining. Moreover, the fuel which is consumed in the boiler can be of low quality and the products of combustion will have no effect upon the blades of the turbine.

The control of fuel flowing from the source 20a is by means of a simple adjustable orifice in the case of gaseous fuel and in the case of liquid fuel a simple carburetor can be used.

Having thus described my invention what 1 claim as new and desire to secure by Letters Patent is:

1. A boiler system of the kind including a boiler chamber in which pulverized fuel is to be consumed, and means for admitting combustion air and pulverized fuel to the boiler chamber said means comprising a combustion chamber, an air-fuel mixture burner disposed in the combustion chamber, a first compressor for delivering dilution air to the combustion chamber, a second compressor for delivering an air-fuel mixture to the burner, a turbine driven by the heated gases leaving the combustion chamber, a shaft interconnecting the turbine and the compressors whereby the compressors are driven by the turbine, said turbine being disposed intermediate the combustion chamber and the boiler, first conduit means through which the gases leaving the combustion chamber are fed to the boiler as combustion air, a container for said pulverized fuel, pipe means connecting the container to the boiler chamber, and second conduit means through which air under pressure from said first compressor flows to the container to force the pulverized fuel into the boiler chamber. 

1. A boiler system of the kind including a boiler chamber in which pulverized fuel is to be consumed, and means for admitting combustion air and pulverized fuel to the boiler chamber said means comprising a combustion chamber, an air-fuel mixture burner disposed in the combustion chamber, a first compressor for delivering dilution air to the combustion chamber, a second compressor for delivering an air-fuel mixture to the burner, a turbine driven by the heated gases leaving the combustion chamber, a shaft interconnecting the turbine and the compressors whereby the compressors are driven by the turbine, said turbine being disposed intermediate the combustion chamber and the boiler, first conduit means through which the gases leaving the combustion chamber are fed to the boiler as combustion air, a container for said pulverized fuel, pipe means connecting the container to the boiler chamber, and second conduit means through which air under pressure from said first compressor flows to the container to force the pulverized fuel into the boiler chamber. 